Polymer nanofiber scaffold for a heparin/fibrin based growth factor delivery system

Abstract

A growth factor delivery scaffold combines a heparin/fibrin-based delivery system (HBDS) with a backbone based on polymer nanofibers for tissue (e.g., tendon and ligament) repair. The scaffold has improved surgical handling properties compared to the gelatinous consistency of the prior art HBDS system and retains the capability for delivering mesenchymal cells and controlling the release of growth factors. One application for the scaffold is mesenchymal stem cell (MSC) therapy for flexor tendon repair. The scaffold can deliver growth factors in a sustained manner, can be implanted for flexor tendon repair, is biocompatible, and is not cytotoxic. The growth factor delivery scaffold may also be used in the surgical repair of an injury to bone, muscle, cartilage, or other tissues.

What is claimed is: 
     
       1. A growth factor delivery scaffold comprising:
 a plurality of uniaxial polymer nanofiber mats; and 
 a cured fibrin gel on the polymer nanofiber mats; 
 wherein the cured fibrin gel comprises fibrin, heparin, a heparin-binding peptide, a growth factor, and thrombin; and 
 wherein the scaffold comprises alternating layers of the polymer nanofiber mats and the cured fibrin gel. 
 
     
     
       2. The growth factor delivery scaffold of  claim 1 , wherein the polymer nanofiber mats comprise electrospun polylactic co-glycolic acid. 
     
     
       3. The growth factor delivery scaffold of  claim 1 , wherein the cured fibrin gel further comprises mesenchymal stem cells. 
     
     
       4. The growth factor delivery scaffold of  claim 1  wherein a first end of the heparin-binding peptide is cross-linked to the fibrin, a second end of the heparin-binding peptide is electrostatically bonded to the heparin, and the growth factor is bonded to the heparin. 
     
     
       5. The growth factor delivery scaffold of  claim 1 , wherein the scaffold comprises six alternating layers of the polymer nanofiber mats and the cured fibrin gel. 
     
     
       6. The growth factor delivery scaffold of  claim 1 , wherein the polymer nanofiber mats comprise nanofibers having diameters of from 100 nm to 500 nm. 
     
     
       7. A method of repairing an injured tissue comprising:
 affixing the growth factor delivery scaffold of  claim 1  to the injured tissue, wherein:
 the injury to the tissue is a structural injury; and 
 the growth factor delivery scaffold is affixed within the structural injury; and 
 
 repairing the structural injury of the injured tissue such that the growth factor delivery scaffold is retained at the site of the structural injury. 
 
     
     
       8. The method of  claim 7  wherein the growth factor delivery scaffold is affixed to the injured tissue in a space created by the structural injury, and the structural injury is repaired such that the growth factor delivery scaffold does not bear a load of the injured tissue and the growth factor delivery scaffold is retained within a space created by the structural injury. 
     
     
       9. The method of  claim 8  wherein repairing the structural injury comprises suturing edges of the injured tissue together around the space created by the structural injury. 
     
     
       10. The method of  claim 7  wherein the structural injury is a rupture, tear or break. 
     
     
       11. The method of  claim 7  wherein affixing the growth factor delivery scaffold comprises suturing the growth factor delivery scaffold to the injured tissue. 
     
     
       12. The method of  claim 7  wherein the injured tissue comprises at least one of tendon, cartilage, bladder, muscle, or bone.